In the semiconductor manufacturing process, a semiconductor substrate is subjected to film formation, photolithography, and impurity doping to form active elements such as transistors and diodes, and passive elements such as resistors and capacitors. JP-A 2008-244403 (Kokai) discloses a semiconductor device and a method for manufacturing the same capable of increasing the capacitance of a MOS capacitor without increasing the area of the MOS capacitor.
In the process for manufacturing a semiconductor device including CMOS (complementary metal oxide semiconductor) transistors, active elements such as CMOS transistors are formed in an active region. On the other hand, a dummy active region is defined outside the active region. This dummy active region is subjected to the same process as the active region. However, the dummy active region does not function as active elements. The dummy active region is provided in a prescribed proportion outside the active region on the substrate. Thus, the pressure is made uniform when the insulating film, for instance, formed on the active region and the dummy active region is planarized.
The active region and the dummy active region are both conductive regions made of semiconductor doped with impurity. Furthermore, the active region and the dummy active region are connected through the substrate. Here, a capacitor may be located outside the active region. In this case, to reduce the influence of signals handled in the active region, the capacitor is located off the space above the dummy active region. This makes it difficult to achieve a sufficient capacitance density of the capacitor on the substrate with limited area.